Transitioning from late pregnancy into early lactation puts cows under major strain. Energy demand is increasing just when the appetite drops right on calving time. Unless carefully managed, this period can lead to serious metabolic challenges. During the dry period, the rumen has been functioning at a much lower level, while the uterus has been expanding and reducing rumen volume. This stresses the rumen, disrupting feed intake patterns, depressing immune function, and forcing the liver and metabolism to work overtime. Small setbacks here – a day or two off feed or slower recovery time to full rumination – can result in rapid body condition loss, impacting production and reproduction performance through the following lactation.
Gut function starts with the rumen
Rumen function is integral to performance on our pasture-based farms. When pasture that is high in moisture is combined with a rapidly fermentable carbohydrate source, adding supplements (silage, PKE, palm kernel) or shifting paddocks changes fermentation patterns. The rumen’s microbial community must adapt quickly to maintain a stable pH, efficiently break down fibre, and keep up the steady flow of volatile fatty acid (VFA) to the liver, where they are converted to glucose, the cow’s primary energy source. When rumen microbes are unbalanced, you see lower intake, poor fibre digestion, loose manure, and lost performance.
Where probiotics come in
Probiotics, or direct‑fed microbials (DFMs), are live organisms that influence the gut microbiome. Typical strains include lactobacilli, enterococci, certain yeasts (Saccharomyces cerevisiae) and rumen-derived bacteria. They help stabilise rumen fermentation, boost fibre-digesting populations, mop up oxygen, and support rumen pH, which helps cows maintain appetite and make better use of the feed they eat. In fresh cows, this means steadier intakes, quicker recovery and potentially improved milk yield and composition, but results depend on strain, dose and how they’re used.
Cows naturally pick up these microbes from grazing pasture and soil intake, but not always in sufficient quantity or quality.
Probiotic research
Recent trials on cows at calving have looked at supplementing these rumen-derived microbes and measuring the effects of increased levels on lactation performance, liver function and other metabolic markers. Evidence is promising, particularly with yeasts that stabilise the rumen environment and optimise fibre digestion. Research is generally positive, but it has proven that not all probiotics perform the same. Benefits are greatest when there is probiotic strain-level evidence, a sufficient dose, and a correctly balanced diet.
What farmers can monitor
- Watch cows at feed time – notice their appetite, how many cows stand off the feed pre-calving and how quickly they rejoin after calving.
- Monitor rumination – note any sudden drops in rumination minutes, as this indicates trouble.
- Check manure consistency – loose, slimy, or very watery manure after a feed change indicates rumen upset.
- How is their milk response? Track peak milk and early lactation yield against previous seasons.
- Keep an eye on their post-calving recovery, especially their return to normal appetite, the proportion of cows recovering within 48-72 hours, and any incidence of milk fever, ketosis and metritis.
- Monitor body condition – aim to avoid any pre-calving loss and target 4.8- 5.2 at calving.
How to use probiotics well
Probiotics work best as part of a well-run nutrition plan: correct energy (90–110% maintenance pre-calving), fibre to keep the rumen working, DCAD management, balanced minerals and minimal social stress. When choosing probiotics, choose products that have been strain tested to achieve robustness and good replication rates in the rumen environment. Use the correct bacterial type and dose, remembering that the rumen has a large capacity and the levels that may have worked well for calves may be insufficient for lactating dairy cows. Discuss delivery options with your nutritionist, as the probiotic used may be influenced by your feed system.
Get the timing right
Start probiotic support before calving, continue through the fresh cow period and during any early lactation feed changes. This is when the rumen microbial community is most vulnerable and when stabilising fermentation delivers the biggest payback.
Sources
DairyNZ – Feeding transition cows: https://www.dairynz.co.nz/animal/nutrition/feeding-transition-cows/
Journal of Dairy Science – Effects of peripartal rumen-derived direct-fed microbial supplementation on lactation performance: https://www.sciencedirect.com/science/article/pii/S0022030224013468
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